A quantitative methodology to determine formation constants that takes into consideration the 27AlNMR signals of Al(III)H2O systems has been analyzed, where area fractions beneath the peaks recorded were associated with the corresponding species fractions. The values of the formation constants were compared with the model obtained by potentiometric studies. In agreement with previous reports, the log*β values obtained by NMR and potentiometry, at 0.020 M ≤ [Al(III)]total ≤ 0.500 M are 12.96 ± 0.02 for Al(OH)3, 13.50±0.02 for Al3(OH)45+, and 109.70±0.09 for Al13(OH)327+, by assuming that Al(OH)2+ has a value of 5.29. Additionally the equilibrium constant values obtained allowed fitting of the conductimetry titrations in the 6.00(103) M ≤ [Al(III)]total ≤ 0.120 M. The algorithm presented in this work gives a support to establish that the area fractions of NMR signals are proportional to the species concentration fractions.

The authors wish to acknowledge CONACYT for the grants given to JCBP, and MLPH to undertake their postgraduate studies. Thanks are also given to PEMEX and IMP (through the project FIES9631III) for partial financing support. The authors are indebted to Dr I. Puigdomenech and Prof. Josef Havel for the copy of the program MEDUSA, as well as to Dr A. Vacca and Dr P. Gans for the copy of the program SUPERQUAD and, finally, to Dr. Mario A. RomeroRomo and to Prof. William F Reynolds for helpful comments.